Recommend obtaining a replacement window/frame and assembly hardware
before beginning this task. Suggest trying to order directly from Airstream.

1) Remove as much of the loose glass from the frame as is safely possible. Use a shop vacuum to remove the glass shards from inside the trailer.
2) Center punch each rivet head to start the drill as close to the center as possible. (~20 minutes)
3) Use a variable speed electric drill (not battery powered) with a 5/32 diameter, sharp drill bit.
a. Use just enough pressure and speed on the drill to create a long, continuous chip. A little practice will help achieve this. Using a fast drill speed and pushing too hard will just make you tired. And you may end up pushing the drill bit through trim on the inside of the trailer, as it breaks through the rivet body.. If you are drilling several rivets out (~50 or more) check the sharpness of the drill bit and regrind to sharpen if needed.
b. Removing the large rivet head from the drill bit can be a challenge. My technique is to reverse the drill motor slowly while I am holding the rivet head with pliers. Comes right off. (total time: 3 hours for 84 rivets)
4) Using a box knife, split the center of all visible caulking lengthwise on the inside of the window housing, that is attached to the old window frame. This will ease removal of the window frame from the housing. Be careful to not cut yourself on any residual glass in the frame. (~2 minutes)
5) Remove the old window frame from the window housing. Use a mallet and 2x2x2 solid piece of wood. From the inside, begin at a corner of the old frame using the piece of wood as a punch. Alternately, give each corner area of the window frame several blows and you will see light begin to come through. The frame/caulk seal will give away and the frame can then be removed by hand. (~2 minutes)
6) Remove the existing caulking from the housing: Actually, I found (after trying every solvent I could find...xylene working the best...but still an arduous task) that a heat gun worked really well. Softened it right up, and let me scrape it off with a plastic putty knife. The heat gun I used was meant for de-soldering printed circuit boards, so it has a very small nozzle...just about perfect for a bead of vulkem. (From the internet)
I used a metal putty knife and carefully removed the caulking from the internal housing. When down to mostly bare aluminum I used mineral spirits on a shop rag to do the final caulk removal. Then I washed all surfaces with hot water and liquid detergent. I tried a heat gun but it was not as effective as I had hoped. (~4 hours) (Later found an excellent solvent as described below.)
7) Using one of the new Olympic rivets I checked all of the holes in the housing with the rivet shank to assure problem free assembly.
8) The replacement window arrived. The box was undamaged. The window assembly was packed in large bubble wrap and supported inside the box by special cardboard ribs. The packing slip attached to the shipping box indicates the assembly came from the Airstream company. (part #372088-100 Wind. Cor. Wrap. RS Frt. CS Rear). I sent an email to the Airstream factory requesting any tips for installing the window they might have.
9) Mary and I lifted the window assembly into the trailer housing and determined all is well with about ¼ outward bow across the middle top and bottom and about 3/16 of clearance all around the inside of the frame for caulking.
10) Received a call (22 Aug 2014) from Dan at the Airstream factory, regarding my email query. He advised me to screw the window in place first, working from the vertical straight edge near the center window, then going around the remainder of the frame, again using screws first, then finally rivets. He said that he has had as much as 2 of bowing and twist and still safely mounted a window. He said that the window glass could be gently moved inside the frame if needed, using a putty knife or tapping with a piece of wood. (Dan, (937)596-6111 x7408 Airstream in Ohio, if I need more advice.)
11) I shall proceed to open all of the holes in the window frame to .166 diameter. Presently they are too small for the rivets. Turns out some of the holes in the new frame did not line up with the holes in the housing so had to be drilled anew using holes in the new frame as the template.
12) Began installing the new window by injecting a small bead of the Vulkem polyurethane caulk all around the inside of the window frame, then lifting the window/frame into place with the straight edge aligned with the straight edge of the existing center window. Used 2 screws (existing screws gathered in the trailer over the years) to fasten the window in the opening, then observed where modifications would be needed for a final fit. This is where the work began! Had to make modifications in the wall which supports the far end of the window frame. Turns out the frame on the new window is about 3/8 longer than the older frame. (Better than too short!) A good friend assisted me in this part of the installation and he has a special vibrating saw tool designed for cutting materials in very tight places and this saved me a lot sweat and concern. Sheet metal was trimmed to facilitate installation of the frame which in turn was fastened into place with a few more screws, then the 84 rivets were installed (screws were removed when approached), trimmed with a nose end wire cutter (not a side cutter), then carefully polished with a small Black and Decker electric hand tool with a ¾ diameter x ½  long emery paper cylinder (replaceable) tool. I did not have access to a rivet head polishing tool. Rivets were installed alternately: 2 or 3 on the top, then 2 or 3 on the bottom, working from the front to the rear. I was pleased to see the ¼  gap between the frame and the trailer housing disappear as the rivets were installed! Be sure to remove the screws, as you progress to the rear, so they do not prevent the proper seating of the frame against the trailer housing! (~8 hours)
13) Some of the Vulkem caulking ended up on the aluminum trailer skin and squirted out all around the window frame. This stuff is tough to remove. I found a solvent that did a fine job of removal with very little effort: Klean Strip Premium Stripper Paste, available at Wal-Mart and Home Depot. It is a paste/jell product, not liquid, is applied with a paint brush and is very easy to use. Works almost instantly in removing the caulk residue. Follow the instructions carefully! This is powerful stuff. (~1 hour)
14) I used the same caulk material on the inside of the trailer, placing a thick bead all around window frame then dipping my fingers into a warm solution of water and detergent (to prevent the caulk from sticking to my fingers), gently forced that material into the space between the window frame and the housing. (~10 minutes)
15) About 3 days later after the caulking had cured and was no longer sticky, I finished by re-installing the plastic internal trim around the window, then the window drapery and vacuumed the couch and carpet. Ready to go again!!!
16) Would I do this again? Probably not as I am 81 years old and not as physically flexible as I used to be. But Im glad that I was able to do it this time with some help from a very good friend. And the repair looks good.